Today, merchants are selling on multiple sales channels to attract new customers, as the competition is fiercer than ever. To stay ahead, they rely on eCommerce SaaS tools to automate key business functions and streamline operations. However, behind that seamless experience lies one of the biggest technical challenges for SaaS developers: integrating with multiple eCommerce APIs.
The more platforms your eCommerce app supports, the greater your chances of capturing a larger share of the market. But with so many APIs available, which ones should your SaaS prioritize?
In this article, we’ve compiled a list of the most in-demand eCommerce APIs based on integration trends among our clients. Use this as your guide to better understand current market demand and decide which integrations to focus on first.
Let’s dive in.
What is an eCommerce API?
An eCommerce API (Application Programming Interface) is a bridge that enables your SaaS solution to connect with shopping systems and marketplaces like Shopify or Amazon. APIs allow you to retrieve, add, update and sync store data like products, orders, customers, categories, etc.
Each API has its own specifics, different data structures, and limitations that demand proper investigation before integration development. That’s why many SaaS companies rely on unified API integration strategies to simplify the connections and scale faster.
Top 13 Popular eCommerce APIs SaaS Usually Integrate With
Below is the list of popular eCommerce APIs, their specifics and integration difficulty ratings. The rating is based on our devs real experience working with each eCommerce API (where 1 = very easy, 10 = very difficult).
1) Shopify API
Shopify has recently moved from REST API to GraphQL API, so apps that want to integrate with this platform should deal with this new type of API.
Active stores: 6M.
Countries: United States, United Kingdom, Australia, Germany, Canada.
💡Integration difficulties: 6/10
WooCommerce REST API enables to access and manage WooCommerce (Wordpress) store data via REST architecture and JSON format. It supports Basic Auth (through API keys) and OAuth.
Active stores: 6M.
Countries: United States, United Kingdom, India, Germany, France.
💡Integration difficulties: 3/10
3) eBay API
eBay provides a set of APIs (Trading API, Inventory API, Order API, Fulfillment API) to work and manage eBay store data. It supports OAuth 2 authentication and has detailed documentation, as well as rate limits.
Active sellers: 18M.
Countries: United States, United Kingdom, Germany, China, Australia, Italy.
💡Integration difficulties: 7/10
Its API is based on the REST architecture and JSON format and also a GraphQL Storefront API designed for headless commerce. It supports OAuth 2.0, offers clear documentation, and includes webhooks for real-time synchronization.
Active stores: 40K.
Countries: United States, United Kingdom, Australia, Canada, Brazil.
💡Integration difficulties: 4/10
5) Etsy API
It uses REST architecture with JSON and supports OAuth 2.0 for authentication. A key difference compared to other APIs is its strong focus on unique, handmade, and vintage items, which means the data structure and workflows often differ from standard eCommerce platforms.
Active sellers: 5M.
Countries: United States, United Kingdom, Canada, Germany, Australia.
💡Integration difficulties: 6/10
Read an article "Webhooks vs Polling: Which is Better for Your eCommerce SaaS"
6) Magento 2 API / Magento (Adobe Commerce) API
Magento (now Adobe Commerce) offers both REST and GraphQL API. While the API is powerful and flexible, developers often face issues with performance, inconsistent endpoints, and version differences across stores.
Active stores: 100K.
Countries: United States, United Kingdom, Netherlands, Germany, Italy.
💡Integration difficulties: 4/10
7) Bol.com API
Bol.com is one of the largest online marketplaces in the Netherlands and Belgium, and its API is designed to let sellers and integrators manage product listings, offers, orders, and shipments. The API is REST-based, uses JSON, and requires OAuth 2.0 authentication.
Active sellers: 46K.
Countries: Netherlands, United States, Belgium, United Kingdom, Germany.
💡Integration difficulties: 7/10
PrestaShop provides a REST API, uses XML or JSON and relies on a key-based authentication system. As with WooCommerce, PrestaShop is open-source and self-hosted, which means every store may run a different version or use custom modules that affect the API’s behavior.
Active stores: 200K.
Countries: United States, France, Spain, Poland, Italy.
💡Integration difficulties: 3/10
9) Demandware (Salesforce Commerce Cloud) API
Salesforce Commerce Cloud, formerly Demandware, offers a set of APIs (including OCAPI – Open Commerce API, and SCAPI – Salesforce Commerce API) to access and manage storefront data. Unlike open-source platforms, SCAPI is part of a fully managed SaaS solution, which ensures stability and enterprise-grade scalability.
However, integration is more complex due to strict authentication, permissions, and multi-tenant architecture, and often requires certification or partnership with Salesforce. Documentation is comprehensive, but the learning curve is higher compared to most other APIs.
Active stores: 11K.
Countries: United States, United Kingdom, France, Germany, Indonesia.
💡Integration difficulties: 7/10
Lightspeed provides a REST API t, uses OAuth 2.0 authentication and returns data in JSON format. A notable characteristic is that Lightspeed supports multi-store and omnichannel setups (eCommerce + POS), which makes it appealing for SaaS tools targeting retailers who operate both online and offline.
However, developers often face rate limits and certain endpoint restrictions, which can complicate large-scale synchronization.
Active stores: 12K.
Countries: Netherlands, United States, Canada, Belgium, Germany.
💡Integration difficulties: 6/10
11) Shopware API
Shopware offers both REST and GraphQL APIs, uses OAuth 2.0 authentication and provides webhooks for real-time updates. Unlike SaaS solutions such as Shopify, Shopware can be deployed in different environments (cloud or self-hosted), which means integrations may vary depending on the version and hosting setup.
While the API is modern and feature-rich, developers often encounter challenges with version fragmentation and custom extensions that affect stability.
Active stores: 21K.
Countries: Germany, United States, Switzerland, Austria, Netherlands.
💡Integration difficulties: 3/10
It is REST-based, uses JSON, and requires OAuth 2.0 authentication. A distinctive aspect compared to other APIs is Walmart’s strict onboarding and approval process, along with compliance requirements for product data and fulfillment standards. The API also includes features for Walmart Fulfillment Services (WFS), making it attractive for SaaS solutions focused on logistics and order management.
However, integration can be challenging due to complex authentication, rate limits, and mandatory compliance checks.
Active sellers: 151K.
Countries: United States, Mexico, Canada, Chile, China.
💡Integration difficulties: 8/10
13) Amazon SP API (Selling Partner API)
Amazon’s SP-API is a suite of REST endpoints covering listings, catalog, orders, reports/feeds, notifications, and FBA (inbound/outbound) for both Seller and (separately) Vendor programs. It uses OAuth 2.0 (Login with Amazon) plus AWS SigV4 signing, strict scopes/roles, and Restricted Data Tokens (RDT) for PII access. Powerful and comprehensive, but the security model, onboarding, and compliance (PII, data retention) add notable complexity.
Active sellers: 2M.
Countries: United States, Japan, Germany, India, United Kingdom.
💡Integration difficulties: 8/10
API2Cart: Unified eCommerce API Integration Solution
Integrating your eCommerce SaaS with multiple shopping platforms and marketplace is no small feat. Each platform like Shopify, Magento, WooCommerce, Amazon, and others comes with its own API structure, data formats, and maintenance challenges. Building and supporting these integrations in-house quickly drains resources and slows down your growth.
That’s where a unified eCommerce API like API2Cart comes in. With just one integration, your application gains seamless access to 60+ shopping carts and marketplaces. This not only cuts your development time by over 80% but also drastically reduces ongoing maintenance efforts.
Whether you're building a multichannel inventory system, shipping automation tool, order management solution, or any other SaaS for online retailers, API2Cart makes platform connectivity simple, reliable, and scalable.
It provides 100+ unified API methods to get, add, update and sync store data like orders, products, customers, shipment, categories and many other valuable info.
Start your free 14-day trial and see how simple eCommerce API integration can be.
Top comments (6)
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Really useful insights.
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